This invention relates to a device for the detection and indication of the presence of electrically conductive particles in a stream of fluid, particularly in an oil supply line.
Indicators for detecting blockage of filter pores by fine particles are known in which the pressure difference between supply and discharge flows is indicated by a pressure difference valve. Significant pressure differences are produced only when a certain proportion of the filter pores are blocked by particles, usually fine particles, and where large particles are involved which do not necessarily enter the pores of the filter, this type of indicator is not sufficiently effective.
In an installation such as a hydraulic system, in which oil is passed through pumps and other components with moving parts, defects or heavy wear usually result in the production of metal detritus or particles which enter the oil stream. These particles, which may be either fine or large according to the nature of the defect in the component are removed by the normal filtration device in the oil line. Unless there is produced a quantity of fine metallic particles sufficient to cause substantial blockage of filter pores, known indicators dependent on pressure differences are not sufficiently sensitive to provide early warning of the presence of material resulting from excessive wear or drainage to components such as pumps.
The present invention seeks to provide a device which will give an early warning of the presence of electrically conductive particles, such as metal detritus in an oil or other fluid stream.